Maciej Dems

PlaneWave Admittance Method- a novel approach for determining the electromagnetic modes in photonic structures.

In this article we present a novel approach for determining the electromagnetic modes of photonic multilayer structures. We combine the plane wave expansion method with the method of lines resulting in a fast and accurate computational technique which we named the plane wave admittance method. In addition, we incorporate perfectly matched layers at the boundaries parallel to the multilayer surfaces which allow for easy determination of leaky modes. The convergence of the method is verified for the case of photonic crystal slab showing very good agreement with the results obtained with full three-dimensional plane wave expansion method while the numerical effort is largely reduced. The numerical implementation of the method will be soon available on the web.

Single mode condition and modes discrimination in photonic-crystal 1.3 μm AlInGaAs/InP VCSEL

We determine the single mode condition and analyze the modes discrimination of 1.3 mum InP based photonic-crystal vertical-cavity surfaceemitting diode laser. To this aim we apply the fully vectorial, three dimensional Plane Wave Admittance Method and analyze a broad range of photonic-crystal parameters such as hole etching depth, distance between the holes and their diameters.

Numerical Methods for modeling Photonic-Crystal VCSELs

We show comparison of four different numerical methods for simulating Photonic-Crystal (PC) VCSELs. We present the theoretical basis behind each method and analyze the differences by studying a benchmark VCSEL structure, where the PC structure penetrates all VCSEL layers, the entire top-mirror DBR, a fraction of the top-mirror DBR or just the VCSEL cavity. The different models are evaluated by comparing the predicted resonance wavelengths and threshold gains for different hole diameters and pitches of the PC. The agreement between the models is relatively good, except for one model, which corresponds to the effective index method. The simulation results elucidate the strength and weaknesses of the analyzed methods; and outline the limits of applicability of the different models.

Optimal Parameters of Photonic-Crystal Vertical-Cavity Surface-Emitting Diode Lasers

We investigate the modal characteristics of a 1300-nm InP-based photonic-crystal (PC) vertical-cavity surface- emitting diode laser. To this aim, we apply the plane-wave admittance method and analyze a broad range of PC parameters such as hole etching depth, distance between the holes, and their diameters. We determine a range of technologically feasible PC parameters providing an optimal laser performance.

Optimal radii of photonic crystal holes within DBR mirrors in long wavelength VCSEL

The modal characteristics of a Photonic-Crystal Vertical-Cavity Surface-Emitting diode Laser (PC-VCSEL) have been investigated. Photonic crystal structure, realized by a regular net of air holes within the layers, has been etched in the upper DBR mirror. An advanced three-dimensional, vectorial electromagnetic model has been applied to a phosphide - based device design featuring InGaAlAs active region, AlGaAs/GaAs mirrors and a tunnel junction to confine the current flow. For the structure under consideration a single mode operation has been found for the hole diameter over photonic crystal lattice constant ratio between 0.1 - 0.3.

Monolithic high-index contrast grating: a material independent high-reflectance VCSEL mirror

In this paper we present an extensive theoretical and numerical analysis of monolithic high-index contrast grating, facilitating simple manufacture of compact mirrors for very broad spectrum of vertical-cavity surface-emitting lasers (VCSELs) emitting from ultraviolet to mid-infrared. We provide the theoretical background explaining the phenomenon of high reflectance in monolithic subwavelength gratings. In addition, by using a three-dimensional, fully vectorial optical model, verified by comparison with the experiment, we investigate the optimal parameters of high-index contrast grating enabling more than 99.99% reflectance in the diversity of photonic materials and in the broad range of wavelengths.

Impact of the hole depth on the modal behaviour of long wavelength photonic crystal VCSELs

We investigate the modal characteristics of a telecommunication-oriented, phosphide photonic crystal vertical-cavity surface-emitting laser (VCSEL) as a function of the hole depth by using a three–dimensional, full vectorial plane-wave admittance method. The interplay of diffraction–waveguiding is considered and the optimal depth of the photonic crystal holes is determined, providing single mode operation with the smallest etching depth of the photonic crystal structure.

Double-diamond high-contrast-gratings vertical external cavity surface emitting laser

A new design of vertical external cavity surface emitting laser (VECSEL) with diamond-based high contrast gratings is proposed. The self-consistent model of laser operation has been calibrated based on experimental results and used to optimize the new proposed device and to perform comparative thermal and optical analysis of conventional and double-diamond high-contrast-grating VECSELs. The proposed design considerably reduces the dimensions and complexity of the device and provides up to 80% increase of the maximum emitted power as compared with the conventional design.

Optimal photonic-crystal parameters assuring single-mode operation of 1300 nm AlInGaAs vertical-cavity surface-emitting laser

We present a self-consistent analysis of InP-based 1300 nm AlInGaAs photonic-crystal vertical-cavity surface-emitting lasers (PhC VCSELs) and tunnel-junction PhC VCSELs, and analyze the influence of the electrical confinement, the PhC hole diameter and etching depth, and the size of the single defect optical aperture on the threshold current and the transverse mode discrimination. We also investigate the thermal performance of the two VCSEL configurations. As a result we determine the optimal PhC parameters assuring stable, single-mode operation in a broad range of driving currents.

Modal gain and confinement factors in top- and bottom-emitting photonic-crystal VCSEL

We investigate the modal characteristics of a phosphide photonic-crystal vertical-cavity surface-emitting diode laser (VCSEL) by using the three-dimensional, full vectorial plane wave admittance method. A single-defect, photonic crystal is defined as a regular, hexagonal net of holes with varying depths. The modal gain and confinement factors are compared for two VCSEL structures: with emission either through the DBR with the photonic crystal or through the DBR free of photonic crystal. Significant improvement in the beam quality is demonstrated for the second design.